[SOLVED] Howto change font style for Window Buttons plugin (Manjaro)

Hi, I'm working with Manjaro XFCE version 17.1.0 with theme Adapta-Nokto-Eta..it works very well, except I would like to change font style for Windows Buttons plugin giving it a bold style and uniform the look with other plugins in my main panel bar (date/time, action buttons, weather update, etc).

I've tried to put in ~/.gtkrc-2.0 (that works in my other Linux Mint 18.3 system):